Lithium and lithium compounds are used in a wide range of fields such as ceramics, secondary battery materials, refrigerant adsorbents, catalysts, medicines, etc. and have attracted attention as nuclear fusion energy resources. If high-capacity batteries, electric vehicles, etc. are commercialized, it is expected that the demand for the lithium and lithium compounds will also increase. When considering that the world's reserves of lithium commercially available are only about 4 million tons at this point, there is an urgent need for developing a new technology for ensuring lithium resources. To this end, extensive studies aimed at efficiently extracting lithium dissolved in a small amount in aqueous solutions such as seawater, bittern, waste fluids of lithium batteries, etc. have continued to progress. The main concern of these studies using lithium adsorbents is to develop a high-performance adsorbent having high selectivity to lithium ions and excellent adsorption and desorption performance.
Conventionally, as a result of these studies, there is known a method for preparing a powder that facilitates adsorption and desorption of lithium by a solid-state reaction or gel process using manganese oxide, and the powder prepared by such a method has been used as a material for a positive electrode for a lithium secondary battery (Korean Patent No. 10-0245808, Korean Patent Publication No. 10-2003-0028447, etc.), a material for a lithium adsorbent, etc. However, the use of a lithium adsorbent in the form of powder in seawater or in a solution where lithium ions are dissolved is inconvenient in handling, and thus it is necessary to mold the powder. As a molding method, Korean Patent Publication No. 10-2003-0009509 discloses a method for preparing an adsorbent in the form of beads by mixing a powder with an alumina powder and agglomerating the mixture of the powder and the alumina powder using a pore-forming agent such as PVC.
Typically, the lithium adsorbent must maintain physical and chemical stability in aqueous solutions in various environments and provide an adsorption site that can ensure high adsorption efficiency. Moreover, the lithium adsorbent must have essential characteristics that can maintain high selectivity to lithium ions that the adsorbent in the form of powder has so as not to adsorb elements other than lithium and facilitate desorption for recovery of lithium after the adsorption. However, when the adsorbent is prepared in the form of beads by the above-described conventional PVC addition method, its handling is easy, but its adsorption capacity is reduced by about 30% compared to the adsorbent in the form of powder, and various problems such as high manufacturing costs, environmental pollution, etc. occur.